Well, I noticed a lot of people put these threads up... So, yeah, you can ask me whatever, I'll try to reply within a few days. Enjoy!
I can't really think of any particular one... Most characters (human and Pokémon) get at least some fanfics even out of just the ones on fanfiction.net. Obviously, some characters get used more than others, but there aren't many that are never used. One thing I would like to see more of is good OC (original character) books not the corny self-insert kind (though those can sometimes be good if the author is skilled at that) but really strong original characters that are interesting and fun to read about.
Well, obviously I know English... For other languages, I know a decent amount of Spanish, a small amount of Latin, and I'm just getting the basics of Japanese down (purely so I can watch Pokémon in Japanese).
